Winter legume cover effects on yields of biomass‐sorghum and cotton in Georgia

Abstract

AbstractAmong the many ecosystems services of winter covers, winter legumes have an advantage over winter grain covers by fixing N that may be used by subsequent crops. A 5‐yr study was conducted to compare the biomass yields of five leguminous winter cover crops [Austrian winter pea (Pisum sativum L.), fava bean (Vicia fava L.), narrow‐leaf lupin (Lupinus angustifolius L.), cahaba vetch (Vicia spp.), crimson clover (Trifolium incarnatum L.)] plus rye (Secale cereale L.) and determine the effects of these winter cover crops either harvested or left on the soil on subsequent biomass sorghum [Sorghum bicolor (L.) Moench] and cotton (Gossypium hirsutum L.) yields at two field locations in Georgia. Lupin produced between 4.16 and 9.54 Mg ha−1 biomass, approximately two to four times more than any other cover at both locations every year. Lupin, followed by vetch and winter pea had the greatest positive effect on biomass sorghum yields. Biomass‐sorghum yields after lupin cover were not significantly different whether biomass was retained on the soil by rolling or removed. Seed cotton yields were higher after lupin and vetch . Significantly higher sorghum and cotton yields occurred for rolled covers with crimson clover, winter pea, and fava bean. Averaged over the years and locations, lupin biomass produced approximately 143 kg ha−1 N, more than any other cover. The study suggests that harvested or grazed lupin or vetch covers could give similar benefits to summer row crops compared with traditionally leaving the cover on the soil.